Solvent extracting catalytic cracking feed



Sept. 11, 1962 R. H. HARVEY 3,953,759

SOLVENT EXTRACTING CATALYTIC QRACKING FEED Filed 001:. 11, 19,54 2Sheets-Sheet 1 PRODUCT //FRACTIONATOR 2 CATALYTIC, 3 4 CRACKING Z i E FZONE I5 A ,3 =H'ENOL PHENOL I EXTRACTION BRAFFINATE 4/ TOWER I9 C lE 9LUBE on. 2K5

EXTRACT PHASE TR EATING B D HEAVYGASOIL l8 EXTRACT Fig.|

Inventor: Robert H. Harvey P 1, 1962 R. H. HARVEY 3,053,759

SOLVENT EXTRACTING CATALYTIC CRACKING FEED Filed on. 11, 1954 2Shasta-Sheet 2 Fig.2

EXTRACTION F GAS OIL B= FRESH PHENOL A= LUBE OIL EXTRACT PHASE llO YIELD9o OF CRACKING B\ Ni REMOVED FROM CRACKING FEED,W1./

Fig.3

EXTRACTION OF CLARIFIED OIL-GAS OIL MIXTURES WITH LU BE-OIL EXTRACT A=0% CL. on. IO0% 6.0. B= 3a%c|..ou s7%e.o. c= 50%CL. on. 50% 6.0. o=67%GL. OIL 33% 6.0.

EQUIV. YIELD IIO CRACKING FEED, I VOL% 0 IO 3O 4O 6070 I00 Ni REMOVEDFROM CRACKING FEED,W1.%

lnvemor: Robert H. Harvey BY 0/4/4 Attorney United States Patent Ofilice3,053,759 SOLVENT EXTRACTING CATALYTIC CRACKING FEED Robert H. Harvey,Baton Rouge, La., assignor to Esso gziearch and Engineering Company, acorporation of aware Filed Oct. 11, 1954, Ser. No. 461,550 5 Claims.(Cl. 208-251) This invention relates to the refining of petroleum oilsby means of a catalytic cracking operation. The inventron particularlyprovides a novel process for the upgradng of potential catalyticcracking feed stocks so as to miprove the characteristics of thesestocks for catalytic cracking. The invention includes a method forimproving the value of the heavy gas oil fractions of a petroleum 011for catalytic cracking by the substantial elimination of organiccompounds containing metal contaminants that normally are present in thegas oil. Furthermore, the invention in one of its applications includesprovision for improving the cracking quality of lube oil extracts thathave been extracted from lube oil distillates by solvent extraction. Theinvention includes provision for improving the cracking characteristicsof catalytic cycle oil by elimination of high molecular weight aromatichydrocarbon types which are refractory to crackmg. In one application ofthis invention this removal or reduction is accomplished by utilizingthe spent solvent from lube oil extraction prior to the normal recoveryof this solvent for re-use.

The basic feature of this invention concerns the solvent extraction of amixture of heavy gas oil and catalytic cycle oil. The solvent employedis any one of the conventional solvents having preferential solventproperties for removal of aromatic hydrocarbons. Such solvents includephenol, furfural, nitrobenzene, etc. Solvent extraction of a mixture ofgas oil and cycle stock results in a synergistic removal of constituentsof both the cycle stock and gas oil which are undesirable for catalyticcracking in a manner providing improved yields of high quality crackingfeed stock.

Use of the spent solvent or extract phase of a lubricating oilextraction process for the extraction of the mixture of cycle stock andgas oil is particularly desirable.

In this aspect, the present invention entails the integration of alubricating oil extraction process with a catalytic cracking operationby use of a novel treating process in which the extract phase of thelubricating oil extraction process is contacted with a mixture of cycleoil and heavy gas oil. The raffinate product resulting from thistreating process includes constituents of the lubricating oil extract,the cycle oil, and gas oil which are suitable for catalytic crackingwhile eliminating inclusion of detrimental metal contaminants andrefractory aromatic hydrocarbons.

As indicated, the present invention comprises a relatively complicatedcombination of a Variety of treating steps. This combination is made inorder to achieve the numerous specific objectives indicated above. Inorder to lay a basis for fully understanding the nature and features ofthis invention, attention will be directed to several aspects of thefield involved.

At the present time the process of catalytic cracking is extensivelyemployed for converting high boiling portions of a petroleum crude oilto lighter boiling commercially valuable products including gasoline andheating oils. The feed stock to a catalytic cracking unit ordinarilyconstitutes gas oil fractions of a petroleum crude oil boiling above thegasoline boiling range or boiling above about 430 F. It is economicallydesirable to include most of the highest boiling fractions of apetroleum crude oil, and for this purpose, the feed to a catalyticcracking unit preferably includes constituents of the crude oil boilingup to about 1100 F., or higher. As used herein, the term gas oil is usedto identify this portion of a crude oil boiling in the range of about430 to 1100 F. or somewhat higher. I

For some time it has been appreciated that inclusion of the higherboiling portions of a crude oil in catalytic cracking feed stock causesthe objectionable introduction of certain metal contaminants to thecatalytic cracking zone. Among the metallic contaminants present inheavy gas oil, nickel is particularly objectionable in poisoning thecatalyst used during catalytic cracking so as to decrease theselectivity and life of the catalyst. Recognize ing this problem, therehave been many suggestions aimed at minimizing metal contamination ofgas oil catalytic cracking feed stocks. In this connection, it has beensuggested that metal contaminants can be removed by contacting gas oilwith a solvent such as phenol. The extraction of gas oil with phenoldoes result in a decrease in metal contaminants, but at an economicallyprohibitive cost. This results from the fact that the phenol acts as aselective solvent to remove constituents of the gas oil which aredesirable for catalytic cracking as well as the undesired metalcontaminants. As a result, phenol extraction of gas oil conducted tominimize metal contamination of the gas oil provides a rafiinate productin yields of only about 60 to volume percent, depending on thecontacting conditions and the nature of the gas oil. The remainder ofthe gas oil is present in the extract phase resulting from thisextraction process together with the organic compounds containing themetallic contaminants removed from the raflinate. Since it is desired touse the hydrocarbons. presentin the extract portion of the gas oil forcatalytic cracking feed as well as the raffinate portion, it is apparentthat this process does not provide the desired objective of separatingthe metal contaminants from gas oil hydrocarbons usable as catalyticcracking feed. V

A basic feature involved in the present invention is the discovery thatphenol can be used to selectively extract organic compounds containingmetallic contaminants from a gas oilwhile avoiding extraction of thedesirable hydrocarbon constituents of gas oil. This is possible byinclusion of high molecular weight aromatic hydrocarbons in theselective solvent-gas oil extraction system. The included high molecularWeight aromatic hydrocarbons serve to displace components of gas oilnormally extracted by the solvent while actually aiding extraction ofmetallic constituents by the selective solvent.

The precise mechanism of this process is not fully understood, but ithas been found that the high molecular weight aromatic hydrocarbonspresent in the highest boiling fractions of catalytic cracked productsprovide the requisite function. Consequently, one aspect of the presentinvention entails the contact of a heavy gas oil with a selectivesolvent in the presence of aromatic hydrocarbons obtained from cycle oilderived from a catalytic cracking process. Again it has been found thataromatic hydrocarbons present in the extract phase of a lubrieating oilextraction process can be used to improve extraction of metalcontaminants from gas oil. In its most .specific and preferred aspect,therefore, the present invention involves the contact of the gas oilwith a selective solvent in the presence of aromatic hydrocarbons fromboth a lubricating oil extract phase and from cycle oil.

Principles of this invention are illustrated in the accompanyingdrawings, in which:

FIGURE 1 illustrates in diagrammatical form a preferred flow planembodying all features of the invention.

FIGURE 2 graphically illustrates the result of extracting a gas oil witha selective solvent by itself and in the Patentedsept. 11, 1962 presenceof aromatic hydrocarbons obtained from the extract phase of alubricating oil; and

FIGURE 3 graphically illustrates the results obtained in the preferredconduct of this invention entailing contact of a mixture of catalyticcycle oil and gas oil with the extract phase obtained from the solventextraction of a lubricating oil.

Referring first to FIGURE 1 of the drawings, the processing stepsinvolved in the practice of this invention are illustrated. In FIGURE 1,the numeral 1 designates a catalytic cracking zone. The operationconducted in zone 1 may constitute any desired type of catalyticcracking operation. Thus, the catalytic cracking may constitute thefixed bed type of cracking, moving bed type of cracking, or fluidizedcatalytic cracking. In each of these types of operation any of thevarious well known cracking catalysts may be employed. Generally, suchcatalysts are the metal oxide types and preferably includesilicaalumina, silica-magnesia, or silica-gel promoted with metal oxideswhich are adsorbed thereon. Cracking conditions require maintenance oftemperatures in the range of about 750 to 105 F., and pressures rangingfrom atmospheric to somewhat above atmospheric pressure. The catalyticagent employed is regenerated intermittently or continuously in order torestore or maintain the activity of the catalyst.

In accordance with this invention, a particular catalytic cracking feedstock as derived in the manner described hereinafter is introduced tocatalytic cracking zone 1 through line 2. For the present, it issufficient to note that the feed to catalytic cracking zone 1 generallyincludes a fraction of a crude oil boiling within the range of about 430to 1100 F. For typical operation, catalytic cracking of this feed stockwould result in con- Version of about 50 to 60% boiling in the gasolineboiling range.

The products of catalytic cracking are removed from the catalyticcracking zone through line 3 for introduction to a product fractionator4 which may constitute one or more distillation zones. Distillation zone4 may be operated to permit removal of light portions of thecatalytically cracked product through overhead line 5, to permit removalof gasoline through sidestream withdrawal 6, and heavier fractions ofthe catalytically cracked products from lower portions of thefractionator. For example, a fraction boiling above about 430 F. andboiling up to about 700 or 860 F. may be removed from the lowersidestream withdrawal 7. Heavy residual fractions of the catalyticallycracked products are removed from the bottom of the fractionator throughline 8. Bottoms withdrawal stream 8 will include hydrocarbons boilingabove about 860 F. and boiling up to about 1150 F. In the event thatpowdered catalyst is employed in the catalytic cracking zone 1, somecatalyst will be entrained in the bottoms withdrawal. In this case theproduct of line 8 may be subjected to a clarification or settlingoperation in order to segregate the hydrocarbons from crackingcatalysts. The product of this operation is commonly called clarifiedoil and the stream of line 8 will be so designated herein.

The fractions of a catalytically cracked product boiling above about 430F. are conventionally called cycle oil and in the process illustratedinclude the streams of both lines 7 and 8. While the process of thisinvention can be employed by using either the streams of line 7 or 8,the invention preferably employs both of these streams as combined inline 9 of the drawings and designated by the term cycle oil.

It is well known that cycle oil of the character identified constituteslow grade catalytic cracking feed stock. Cycle oil particularly includesrefractory high molecular weight hydrocarbons which, if recycled to acatalytic cracking operation, cause excessive formation of gas, coke andtar during catalytic cracking. The constituents of cycle oil which areparticularly objectionable for crackthe lubricating oil.

ing are high molecular weight aromatic hydrocarbons and particularlythose boiling above about 860 F. The aromatic hydrocarbons present incycle oil include polynuclear aromatic hydrocarbons and condensed ringaromatic hydrocarbons. The condensed ring aromatic hydrocarbons areparticularly undesirable for inclusion in catalytic cracking feed stock.As will be seen, the process of this invention provides a means forupgrading cycle oil for catalytic cracking by elimination of theseundesirable aromatic hydrocarbon types.

In accordance with this invention, extract phase from tower 12 and line16 enters the top of tower 11 at point A. Heavy gas oil or line 10,which may constitute the gas oil fraction of a crude oil boiling aboveabout 430 F., is introduced into the bottom of tower 11 at point C.Cycle oil in line 9 enters tower 11 at point B, which is any placebetween point A and point C, or may be ad mixed with heavy gas oil atpoint D, or a portion of it may be admixed at point D with the remainderentering the tower at point B as previously described. The pres entinvention is of particular application to heavy gas oils boiling up to1150 F. or somewhat higher. As indicated, such gas oils arecharacterized by inclusion of organic compounds containing metalliccontaminants such as nickel, vanadium and iron, present in amounts ofabout 0.00002 to 0.001 wt. percent. The process of this invention is ofapplication to such gas oils in permitting removal of the metalcontaminants referred to.

The mixture of cycle oil and heavy gas oil introduced to tower 11 iscontacted with the extract phase of a lubricating oil extractionprocess. The required extract phase may be obtained from the processillustrated at the right of the drawings carried out in the extractiontower 12. In tower 12, a lubricating oil distillate or deasphalted oilconstituting the fraction of a crude oil boiling in the range of about700 to 1100" F. or above, is contacted with a selective solvent adaptedto selectively extract aromatic constituents of the lubricating oil.Phenol is one of the selective solvents which may be employed, althoughother solvents are known such as furfural, nitrobenzene, aniline,cresol, etc. Anti-solvents or solvent modifiers may be used andconventionally are used in conjunction with these solvents for theextraction of a lubricating oil. For example, in the case of phenol,about 1 to 15% or somewhat higher percentages of water are preferablymixed with the phenol or separately injected during extraction, toprovide the best extraction results. It is to be understood therefore,that the lubricating oil extraction process conducted in tower 12 mayconstitute any desired type of extraction operation.

As diagrammatically illustrated, extraction can be conducted byintroducing lubricating oil at the lower portion of an extraction towerthrough line 13. The selective solvent, such as phenol, is introducedinto the top of the extraction tower through line 14. The phenol willmove downwardly through the tower countercurrent to an upwardly movingstream of lubricating oil, permitting extraction of constituents of thelubricating oil by the phenol during this contact. Perforated plates,packing, etc., may be used in the tower to aid this contacting. Arafiinate phase may then be recovered from the uppermost portion of thetower and withdrawn through line 15, constituting a lubricant product.The extract phase removed from the bottom of the tower through line 16will include the spent phenol solvent together with extractedconstituents of the lubricating oil.

In this extraction process, the solvent to oil ratio will ordinarily bebetween about 0.5 to 1 and 3 to 1. When employing phenol or phenol-watermixtures as the selective solvent, a solvent to oil ratio of about 1 tol to 2 to 1 is paticularly suitable. In the case of phenol extraction,the extract phase of line 16 will primarily constitute spent phenolincluding aromatic hydrocarbons extracted from In general, the extractphase, will constitute about 60 to 90% phenol and about 40 to ofhydrocarbons extracted from the lubricating oil feed stock. In addition,dependent on the amount of water injection, about 0.0 to 15.0% of waterwill be included in' the extract phase.

This extract phase resulting from selective extraction of a gas oil toproduce a high quality lubricating oil is usually of value as acatalytic cracking feed stock. Thus, it is known that the portion of alubricating oil extracted by a selective solvent such as phenol isgenerally suitable for cracking. The extracted hydrocarbons for the mostpart constitute single nucleus aromatic hydrocarbons with substitutedalkyl radicals which make the compound sufiiciently paraffinic so thatthey can be attractively subjected to cracking. In the past, the extractphase from a lubricating oil extraction process has been treated so asto separate solvent from these hydrocarbons and the hydrocarbon extractis then used as catalytic cracking feed. However, the necessary solventrecovery facilities for this separation are expensive. It is one of thefeatures of this invention, that this process can be integrated with anexisting lube oil extraction plant without major additions to thefacilities used to recover solvent from extract. In FIGURE 1, extractleaving tower 11 through line 18 is sent to the existing phenol recoverysystem used for tower 12.

The heart of the present invention concerns the operation of treatingtower 11 to which is supplied the extract phase of line 16, the cycleoil stream of line 9 and the heavy gas oil stream of line 10. Byintroducing the mixture of cycle oil and heavy gas oil at the lowerportion of tower 10, and the extract phase at the upper portion of tower10, countercurrent treatment is secured. Phenol present in the extractphase of the lubricating oil will pass downwardly through tower 11,counterfiow to an upward passage of the mixture of cycle oil and heavygas oil. During the ensuing contact, there is a substantial transfer ofhydrocarbon types. Aromatic constituents of the heavy gas oil which maybe selectively extracted by phenol in the lower portion of tower 11 aredesorbed in the upper portion of the tower by the hydrocarbons presentin the extract phase supplied in the top of the tower.- Condensed ringaromatic compounds present in the cycle oil similarly n tend to desorbsingle ring aromatic hydrocarbons brought into the tower with theextract phase. In addition, metal contaminants introduced to the towerin the heavy gas oil are effectively scrubbed from the gas oil so as tobe removable from the tower with spent solvent withdrawn at the bottomthereof. The result of the contacting treat-f ment conducted in tower11, permits removal of an extract phase from the bottom of the towerthrough line 18 constituting phenol, metallic contaminants, and aromatichydrocarbons, particularly constituting condensed ring aromaticcompounds. The raflinate stream withdrawn from the top of tower 11through line 19 will primarily constitute hydrocarbon constituents ofthe lube extract, the cycle oil, and the gas oil which constitute goodcatalytic cracking feed stock. Thus, the raffinate will be moreparaffinic in nature than the cycle oil introduced to the tower, willcontain substantially less metal contaminants than the gas oilintroduced to the tower and will include the hydrocarbons originallycontained in the extract phase supplied to the tower.

Traces of phenol entrained in the rafi'inate stream of line 19 may beremoved from the raflinate by distillation in fractionation zone 20. Thephenol may be-removed overhead through line 2 1 while dephenolizedraflinate will be removed from the bottom of tower 20 through line 2. Itis this raffinate which is supplied to catalytic cracking zone 1 as thefeed to this zone.

It will be seen that the process described employs a novel treatingoperation for concomitant contact of the extract phase of a lubricatingoil extraction process, a heaw gas oil containing metal contaminants anda cycle oil containing aromatic hydrocarbons which are not Talco andNorth Louisana crudes.

6. adaptable for cracking. The single treating operation conductedserves to remove metal contaminants from the raffinate product, servesto recover crackable constituents originally present in the extractphase, and serves to upgrade cycle oil for catalytic cracking.

In order to bring out the unique features and advantages of the processdescribed, reference is made to exemplary data obtained in evaluatingthe process of this invention. In a first series of tests which wereconducted,

experiments were carried out to evaluate the effect of contacting a gasoil with a selective solvent in the presence of high molecular weightaromatic hydrocarbons. The heavy gas oil was derived from a SouthLousiana crude oil and had the following inspections;

In one series of experiments which were conducted, the total extractphase from a lubricating oil extraction operation was employed as thesource of the selective solvent.

The lubricating oil distillate which was phenol extracted was producedfrom a blend of distillates obtained from A typical range of inspectionsfollow for this stream:

Gravity, API 26.5-27.5 Viscosity, SSU/210 F. 39 42 Aniline point, F. 185-195 Diesel index 49 54 This distillate was treated with phenol in acountercurrent extraction tower providing about 5 theoretical stages.The feed rates were about 12,300 b./s.d. of phenol and about 7,450b./s.d. of lube distillate to provide a phenol treat of 1 65 Waterinjection was maintained during extraction to provide a total injectionamount of about 2.5%, based on the phenol. The extraction temperaturewas about 145 F.

The extract phase obtained from this operation, constituted 84% phenol;2% water, and 14% hydrocarbons extracted from the lubricating oil feed.The hydrocarbon constituents of the extract phase were primarilymononuclear aromatic compounds having substantial alkyl side chainsubstitution. Phenol was separated from a portion of this extract phaseand it was found that the hydrocarbon constituents of the extract phasehad the following inspections:

The gas oil identified was extracted with this lubricating oil extractphase and with fresh phenol solvent in comparative extraction testsoperated at about F. The conduct of these extraction tests and theresults of them are shown in Table TABLE II lubricating oil extractphase. In these experiments, the

gas oil was that identified in Table I. N'Ckel Removal From Gas 011 byPhenol Extractwn The clarified oil was obtained from the catalyticcrack- F h L b ing of a gas oil boiling in the range of about 430 to 555i ig 5 1l50 conducted so as to secure about 60% conversion to Phasegasoline. In these experiments lubricating oil extract phase derivedfrom the solvent extraction of a 100 neutral g fi i i gg g ggf meat 0896 lubricating oil was employed. This extract phase con- Waterinjection, i151. percentIII::::::: 9: 7 11.0 stitutfid 18%hydrqcarbor'ls and 82% p The Totfgglifiiggd pitigll 21 2 z 20 8 10spections of the clarified 011 and the hydrocarbons present Conradsoncariiil'fw'clgift'ik'rla'e'rit 2.3 2.61 in the extract phase were asfollows: izulilixirl. weight percent 0.23? g? 10 c p.p.m Aromaticindex.-- 16.8 TABLE In D g p t ,1

op 0110 1Z8 1'8. a e01:

Yield on total oil, vol. percent 75 84.1 011 Clarified Gravity, API 23.5 23. 1 met Phase 011 Conradson, carbon, weight per 1.4 0. 74 Sulfur,weight, percent 0.33 0. 84 Gravity OAPI 17 6 20. 0 93 3 3 Viscosity,ssU72'i0' 46 as Naphthene ma 5 6 Conradson carbon, weight percent- 0. 11.6 Extract n; Sulfur, weight percent 1. 72 72 gravity, API Ca 10 9.7 20g f g g g gl grfffifi ififi' fii gfl' ,2 3 Aromatics, weight percent 6547. 2 Nickel 1 1 Paraflins, weight percent. 35 52.8 Aromatic index 39.038- Ni from cat. cracking feed, weight percent 77 86 Naphthena mdex 9 4Conradson carbon, weight percent..- 51. 3 69. 8 Sulfur, weight percent37. 4 4. 0 25 Different mixtures of the clarified oil and cycle stock vlume pe cent water expressed as percent of phenol. were extracted withthe lubricating oil extract phase at a Includes 011m Spent phenoltemperature of about 160 F. in a manner providing The results shown inTable II establish the fact that about five contacting stages. Theextraction conditions extraction of gas oil is substantially improved byincluand the results secured are summarized in Table IV.

TABLE IV Extraction of Mixtures of Gas Oil and Clarified Oil Feedstock-percent gas oil 67 percent clarified oil 33 Operating conditions:

Spent phenol treat, vol. percent Water injection, vol. percent Total oilfeed blend: 2

Gravity, API Couradson carbon, weight percent Sulfur, weight percentNickel, p.p.m Aromatic in ex Naphthene index- Dephenolized raflinateoil:

Yield on total oil, vol. percent Equiv. yield of crack. feed Gravity,API

Conradson carbon,

Sulfur, weight percent Nickel, p.p.m. plus or minus 1 Removals:

Ni from cat. crack. feed, weight percent Conradson carbon, weightpercent-. Sulfur, weight percent 1 Vol. percent water expressed aspercent of phenol. 2 Includes oil in spent; phenol, heavy gas 011, andclarified 011.

sion of high molecular weight aromatic hydrocarbons, in In this tablethe Equivalent Yield of Cracking Feed this case derived from lubricatingoil. This is particularis determined y the formula ly illustrated inFIGURE 2 of the drawings, based on V V this and similar data showing theextent of metal removal achieved by extraction of gas oil with: (a)phenol includ- V3 ing aromatic hydrocarbons extracted from lubricatingoil, h e; and (b) phenol by itself. The data particularly shows that theextract phase of a lubricating oil extraction process is a better agentfor removing metal contaminants from gas oil than a selective solvent byitself. For this reason, use of such an extract phase is preferred inthe practice of this invention and will be particularly referred to inthe data which follows:

Another series of experiments was conducted to evaluate The mostsignificant data of Table IV is represented the precise flow planillustrated in FIGURE 1 involving graphically in FIGURE 3 of thedrawings. It is there contact of a heavy gas oil with both cycle oil anda shown that the removal of metal contaminants from gas V =Total volumeof rafiinate obtained during a run.

V =The estimated volume of rafiinate that would be obtained if theclarified oil portion of the feed were extracted separately under thesame conditions.

V =Volume of heavy gas oil plus volume of oil associated with thelube-oil spent phenol.

9 oil is improved to provide greater yields of cracking feed byinclusion of clarified oil in admixture with the gas oil. In consideringthe relative proportions of clarified oil and gas oil, it is shown thatincreasing the proportion of the clarified oil in the mixture providesbetter extraction results.

As established, therefore, the present invention broadly concerns theprocess of extracting a gas oil fraction of petroleum employing aselective solvent for aromatic hydrocarbons in the presence of oradmixed With extraneously introduced aromatic hydrocarbons derived frompetroleum fractions boiling above about 430 F. Inclusion of sucharomatic hydrocarbons can be achieved by admixing cycle oil fromcatalytic cracking with the gas oil. Alternatively, or preferably inaddition to this, aromatic hydrocarbons can be derived from thelubricating oil fraction of a gas oil in order to aid the extraction ofgas oil. This is preferably achieved by employing the total extractphase of a prior lubricating oil extraction process for the extractionof gas oil.

What is claimed is:

1. A process for the preparation of catalytic cracking feed stocks whichcomprises contacting a lubricating oil distillate containing aromatichydrocarbons with a selective solvent for aromatic hydrocarbons to forma first extract phase containing said solvent and aromatic hydrocarbons,contacting said first extract phase with a heavy gas oil containingconstituents boiling above about 1100 F., metal contaminants, andadmixed cycle oil, to form a second extract phase containing metalcontaminants derived from said heavy gas oil and a rafiinate phase, andremoving the solvent from said raffinate phase.

2. A process as defined in claim 1 wherein said selective solvent foraromatic hydrocarbons is phenol.

3. A method of pretreating a mixture of cycle oil and heavy gas oil forsubsequent catalytic cracking, said mixture containing constituentsboiling above about 1100 F. and containing metal contaminants, whichcomprises contacting a lubricating oil distillate containing aromatichydrocarbons with phenol to form a first extract phase containing phenoland aromatic hydrocarbons, contacting said first extract phase With saidmixture of cycle oil and heavy gas oil to form a second extract phasecontaining metal contaminants derived from said mixture 10 and araflinate phase, and removing phenol from said raffinate phase.

4. A process for the preparation of catalytic cracking feed stocks whichcomprises contacting a lubricating oil distillate containing aromatichydrocarbons with phenol to form a first extract phase containing phenoland aromatic hydrocarbons, contacting said first extract phase with aheavy gas oil in the presence of a cycle oil, said heavy gas oilcontaining constituent boiling above about 1100 F. and containing metalcontaminants to form a second extract phase containing metalcontaminants de' rived from said heavy gas oil and a raffinate phase,and removing the phenol from the raflinate phase.

5. A process for refining a heavy gas oil fraction containingconstituents boiling above about 1100 F. and containing metalcontaminants which comprises in combination contacting a lubricating oildistillate containing aromatic hydrocarbons with phenol to form anextract phase, contacting the heavy gas oil fraction with said extractphase in the presence of a cycle oil to form a rafiinate fractionsubstantially free from said metal contaminants, thereafter segregatingand catalytically crack ing the hydrocarbons in said rafiinate phase.

References Cited in the file of this patent UNITED STATES PATENTS2,139,392 Tijrnstra Dec. 6, 1938 2,201,550 Van Dijck et al. May 21, 19402,228,510 Dearborn et al. Jan. 14, 1941 2,270,827 Tijmstra Jan. 20, 19422,279,550 Benedict et al. Apr. 14, 1942 2,304,289 Tongberg Dec. 8, 19422,342,888 Nysewander et al Feb. 29, 1944 2,374,102 Iahn et al Apr. 17,1945 2,748,055 Payne May 29, 1956 2,770,576 Pratt Nov. 13, 19562,780,582 Junk Feb. 5, 1957 2,793,168 Corneil May 21, 1957 2,859,172Reymond Nov. 4, 1958 OTHER REFERENCES Wrightson: Analytical Chemistry,vol. 21, No. 12, December 1949; pages 1543-1545.

Woodle et al.: Industrial & Engineering Chemistry, vol. 44, No. 11,November 1952; pages 2591-2596.

1. A PROCESS FOR THE PREPARATION OF CATALYTIC CRACKING FEED STOCKS WHICHCOMPRISES CONTACTING A LUBRICATING OIL DISTILLATE CONTAINING AROMATICHYDROCARBONS WITH A SELECTIVE SOLVENT FOR AROMATIC HYDROCARBONS TO FORMA FIRST ESTRACT PHASE CONTAINING SAID SOLVENT AND AROMATIC HYDROCARBONS,CONTACTING SAID FIRST EXTRACT PHASE WITH A HEAVY GAS OIL CONTAININGCONSTITUTENTS BOILING ABOVE ABOUT 1100*F., METAL CONTAMINANTS, ANDADMIXED CYCLE OIL, TO FORM A SECOND EXTRACT PHASE CONTAINING METALCONTAMINANTS DERIVED FROM SAID HEAVY GAS OIL AND A RAFFINATE PHASE, ANDREMOVING THE SOLVENT FROM SAID RAFFINATE PHASE.